software allows grid operators to monitor and manage the output from large numbers of wind turbines in different locations. The sophisticated electronic controls and capabilities of modern wind turbines have changed the energy equation and made it possible for wind power to actively contribute to grid reliability.
Modern wind turbines can and should be designed to:
- Ride through system faults and continue to supply energy to the system when those faults clear;
- Contribute reactive power and active voltage control for stability of the common grid; and
- Communicate with grid operators and be instructed to limit output or rate of change in output if necessary for grid reliability.
AWEA has proposed a "Wind Grid Code" to quantify these performance requirements (and others) in a cost-effective, non-discriminatory way, and is working with engineers and regulators to ensure that wind indeed contributes its fair share to grid reliability.
What About Transmission?
A wind energy grid code is not sufficient, however. If market rules are inefficient and continue to stifle new competition, being a good citizen will be of little use. Changes are needed in those rules-changes that would benefit consumers, irrespective of wind.
Today, the nation's power markets are governed by more than 200 different tariffs that set the rules and conditions for access to, and use of, the grid. Most of these tariffs assign fixed costs to incremental transactions and impose non-cost-based penalties on generators that deviate from precise advance schedules-causing newer and non-standard resources like wind to bear a disproportionate share of the costs of building and operating the common grid. Meanwhile, some major markets, such as the Pennsylvania-New Jersey-Maryland Interconnection (PJM), operate under a totally different, more efficient tariff that coincidentally happens to be very wind-friendly.
The challenge will be to extract those features from these newer tariffs and apply them to wind generation in more traditional tariffs while enhancing reliability but not shifting costs onto other generators and loads. Several jurisdictions or utility systems have successfully accomplished this, including California, ERCOT, PacifiCorp, and the Bonneville Power Administration (BPA). Where such changes are taking place, the results are dramatic.
In California, where the California Independent System Operator (Cal-ISO) replaced discriminatory, non-cost-based penalties with a requirement that wind generators provide forecasts for their energy deliveries that can be used to assign transmission capacity, the costs for wind to use the common grid are about $2/MWh. By contrast, on the Western Area Power Administration (WAPA) system, which operates under an older tariff, the cost of bringing wind to market is about 10 times more, or $20/MWh, at equivalent penetration levels.
What Does It Cost to Integrate Wind?
So what are the real costs, if any, of utility integration of wind? How can they be defined and measured?
In the United States, a first generation of studies offers some preliminary conclusions. These studies-from Xcel Energy, PacifiCorp, BPA, We Energies, and consultant Eric Hirst-are summarized in a report by the Utility Wind Interest Group (UWIG), 2 an organization of some 55 utilities that have wind power on their systems.
The UWIG survey concludes that the studies